The invention concerns a device for revascularizing muscular tissue by producing a tubular necrosis.
Such devices are known and are finding increasing clinical application, in particular in the field of cardiac surgery.
In the category of xe2x80x9ctransmyocardial laser revascularizationxe2x80x9d, such as laser myocardial revascularization (LMR), predominantly three different laser systems, i.e., pulsed CO2 laser, pulsed holmium-YAG laser, and pulsed excimer laser are currently used, primarily devices from the US companies PLC, CARDIO GENESIS, and United States Surgical Corporation. With these pulsed laser. systems, it is possible, through the use of the mechanism of so-called photoablation, to create transmyocardial channels; and, based on the system, thermally affected marginal zones and also shock waves are produced through the process of photoablation. These systems are extremely expensive, and, even so, amplitude and depth of effect of the shock waves cannot be optimized.
The object of the invention is, consequently, to provide a comparatively simple and economical device for revascularizing muscular tissue, in particular heart muscular tissues, which offers improved possibilities for optimization of the treatment parameters.
The invention includes the technical teaching of providing a device with which, independently of one another, the wall of a tubular necrosis or of the channel generated in the course of revascularization can be deliberately affected thermally and with which shock wave-like pressure amplitudes with separately adjustable parameters can at the same time be generated in the vicinity of the wall.
It also includes the idea of using different energy sources to produce the thermal effects on the one hand and the shock wave effects on the other, in the interest of separate control of the parameters. According to investigations by the inventor, the combined use of HF energy and electrical pulses with relatively high field intensities of an electrical shock wave generator is particularly economical and presents advantageous effects. The HF energy is expediently in the range of a few watts and the pulse field intensity is a few kV/cm.
Surprisingly, it turned out that the use of bifilar, helically wound high frequency electrodes, which are mounted mutually isolated on an puncture needle, causes shrinkage of this tissue upon input of the high frequency energies and distribution in the parietal tissue. After removal of the puncture needle, an open channel remains. At the same time, by deliberate variation of the high frequency energy, the heat introduced into the channel wall can be deliberately varied with a view to the expansion and consistency of the remaining tissue. Similar effects were also obtained with other HF electrode configurations.
By the additional installation of two mutually isolated high-voltage electrodes, which can lie exposed on the end or along the HF application system (the HF puncture needle), it is also possible to produce a spark-like puncture by the brief application of zero-potential high voltage, which in turn produces shock waves in the vicinity.
By variation of the high voltage in the duration of the high-voltage pulse, it is possiblexe2x80x94independently of the introduction of thermally active HF energy via the bipolar HF electrodesxe2x80x94to separately vary the strength of the shock wave amplitudes. Through selection of different bipolar electrode configurations, it is possible to control the thermal coagulation zone.
In a preferred exemplary embodiment, the HF puncture needle is made of a break-resistant ceramic metal composite capillary, on whose outside wall the bipolar HF electrodes are installed and in whose interior the leads of the HP electrodes are guided mutually isolated and attached on the edges of the distal end. However, other suitable materials, such as high temperature resistant plastics (PBEK, PPSU, etc.), may also be used as electrode carriers.
According to a preferred exemplary embodiment, the HF puncture needle is exchangeably mounted in an electrically, mechanically, or hydraulically driven advancing device located in the interior of a hand piece. The hand piece itself is advantageously designed with a distal attachment holder such that during use of the device for perforation of the heart muscle, anchoring in the epicardium is possible and the puncture needle can be inserted under control into the heart muscle by means of the advancing device.
Energy is supplied to the HF electrodes by a bipolar high frequency generator with adjustable output and appropriately adapted terminating impedance; the high-voltage pulse electrodes are supplied by a high-voltage pulse generator.
In further development of the idea according to the invention, to produce larger channel diameters, a rotating hollow knife by which the contour of the channel is cut into the tissue can be provided instead of the puncture needle. The addition of a suction pump on the above-described hand piece makes it possible to aspirate the excess tissue in the interior of the hollow knife.